Multicontact passive semiconductor electrodes have been successfully implanted in the arm area of the supplementary motor area (SMA) of a primate that was trained to do a number of different wrist movement tasks. SMA neurons seem to be better correlated with complex tasks than simple repetitive tasks. Recorded activity diminishes in amplitude after several months but can be temporarily restored with microstimulation through the electrode. Neurons in the SMA have been operantly conditioned and they may prove to be a useful signal source of controlling prosthetic devices. The multicontact silicon electrode developed by the University of Utah, was evaluated for possible incorporation into the studies being conducted by the LNLC. A number of design problems were discovered when the electrodes were implanted at the University of Utah. Further development of the electrode should be left to the University of Utah before we attempt to employ the electrodes at the NIH.